This application claims priority from Japanese Patent Application Reference No. 11-073106, filed Mar. 18, 1999, the entire content of which is incorporated herein by reference for all purposes.
The present invention relates generally to disk drives for computer applications, and specifically to systems and apparatus used in reproducing an optical disk and/or a magneto-optical disk.
Conventional disk drives typically employ a biaxial orthogonal translational objective lens driving unit in which the moving part for holding an objective lens is supported by elastic support members. A perceived advantage of such construction is that the driving unit can be made in a small size at low cost. On the other hand, a lack of rigidity in some support members can cause bending and twisting of some components. Such bending and twisting of support members can result in undesirable power consumption in certain drive dispositions.
For example, if the objective lens driving unit is placed horizontally, the moving part will sink downward in the focusing direction under its own weight. Accordingly, it will be necessary to counter this sinking by supplying an offset current for canceling the sinking of the moving part.
What is really needed is an apparatus for correcting for forces and moments acting upon lens holders in disk drives.
According to the invention, techniques for minimizing power consumption in optical disk drives are provided. Embodiments according to the present invention can provide disk drives with optimal positioning of a fixing part of an objective lens driving unit incorporated therein. Spatial location of magnets can also be determined in order to reduce the power consumption and the torsion of the lens.
In a representative embodiment, an optical disk drive is provided. The optical disk drive can comprise variety of components. For example, a spindle motor for rotating an optical disk can be part of the disk drive. Further, a laser source for generating a light beam can also be part of the disk drive. The disk drive can also include an optical head. The optical head can have an objective lens to converge the light beam onto a recording portion of the surface of the optical disk, a lens holder to hold the objective lens, a plurality of elastic support members to elastically support the lens holder, and a fixing part to fix the elastic support members, for example.
The fixing part, the plurality of elastic support members and the optical head can operatively dispose a front of the objective lens at a working distance from the surface of the optical disk, at a working distance variable between a first working distance, W.D.1, and a second working distance, W.D.2, for example.
The optical head can operatively dispose the objective lens at a distance, L holder, between the front of the objective lens and a center of a plurality of fixing points of the elastic support members on the lens holder in a focusing direction orthogonal to the radius of the optical disk. The fixing part can be operatively disposed at a distance, L wire, between the surface of the optical disk and a center of a plurality of fixing points of the elastic support members on the fixing part in the focusing direction, C wire.
The lens holder can be disposed in a direction orthogonal to the radius of the optical disk and receding from the surface of the optical disk a distance, d, which is the distance the plurality of elastic support members are biased by a weight of the lens holder in a state that the disk drive is placed substantially horizontally.
The disk drive can also include a slider for moving the optical head in a radius direction of the optical disk. The objective lens, the lens holder, the plurality of elastic support members and the fixing part can be disposed to satisfy the relation:
(W.D.1+W.D.2)/2+L holderxe2x88x92d less than =L wire less than =(W.D.1+W.D.2)/2+L holder.
In a specific embodiment according to the present invention, an optical disk drive can be provided wherein the objective lens, the lens holder, the plurality of elastic support members and the fixing part are disposed substantially according to the relation:
xe2x80x83L wire=(W.D.1+W.D.2xe2x88x92d)/2+L holder.
In another specific embodiment according to the present invention, an optical disk drive can be provided in which the optical head also includes a magnet. The optical head can be arranged so that a center position of the magnet in the focusing direction, C mag, can be disposed a distance of substantially d/2 from C wire in a direction orthogonal to the radius of the optical disk and receding from the surface of the optical disk, for example.
In a further specific embodiment according to the present invention, an optical disk drive can be provided in which the optical head may be moved within a movable range having a center. The optical head can be disposed at the center of the movable range, such that a point on the surface of the objective lens in the focusing direction, C lenz, is disposed a distance from the optical disk surface of approximately (W.D.1+W.D.2)/2.
Numerous benefits are achieved by way of the present invention over conventional techniques. The present invention can provide a disk drive in a small size with low cost. Many specific embodiments according to the present invention can operate at reduced power consumption compared with conventional disk drives known in the art. Specific embodiments can reduce the tilt of the disk drive lens. Select embodiments can comprise an optimal mounting position of a disk drive lens carrier""s fixed part and magnets. Some embodiments can provide a disk drive that suppresses an increase of a power consumption arising when different types of disks are reproduced, as well as increases of power consumption and tilt of the lens arising from changes in disposed attitude of the disk drive, for example.
These and other benefits are described throughout the present specification. A further understanding of the nature and advantages of the invention herein may be realized by reference to the remaining portions of the specification and the attached drawings.